Writing & AI tools / Plagiarism checker9 tools
Best plagiarism checkers
Check a text against other sources for copied passages. Facts come from each tool's own pages, and every score says where it comes from. How we rank
- Tools
- 9
- Researched
- 6
- Free option
- 2
- Only listed
- 3
Disclosure: agathox makes some of the tools listed here. They are labelled and scored by the same method as every other tool.
Ranked by signals we can measure or quote: website health, the facts each tool's own pages state, and community discussion. Nothing here has been hands-on tested yet, so this is not a quality test. How the signals rank works
Want two of these head to head? Compare tools side by side.
Details and sources
- Free tier
- Free plan at $0/month: plagiarism checker up to 1,000 words, AI content detector up to 1,000 words, AI summarizer up to 2,000 words, AI humanizer up to 500 words. Trial length not stated.
- Paid plan
- Essential from $14.99/month (100k words/month). Professional from $29.98/month (200k words/month). Yearly prices not stated. Page shows a currency selector (USD, AUD, GBP, CAD, INR, EUR); listed prices are USD.
- Signup
- Not stated. Free plan button links to a signup page.
- Watermark
- Not stated.
- Where files go
- Policy does not say where submitted text is stored; mentions cloud hosting providers and transfers to the US. No retention period for user content. By default user content may be used for AI training, fine-tuning and evaluation; opt-out by email applies going forward only.
From the tool's own pages, checked 2026-11-01. Sources: Pricing, Privacy policy. Prices and limits change; check the tool before you rely on them.
Details and sources
- Free tier
- Not stated.
- Paid plan
- Not stated.
- Signup
- An account is required to begin checking for AI content. The page says: “Create your account for free to begin checking for AI content.”
- Watermark
- Not stated.
- Where files go
- Not stated.
From the tool's own pages, checked 2026-11-04. Sources: Home. Prices and limits change; check the tool before you rely on them.
Read automatically by a program, not by a person. Each fact quotes the sentence it came from, and a fact is shown only if that sentence is on the page. Where a page did not say, it reads “Not stated.”
Details and sources
- Free tier
- Free plan at $0 for limited use: 10K words (100 credits, one time; 1 credit = 100 words). The comparison table instead shows 60 credits renewing daily, so the page is inconsistent. No file upload, PDF download, Deep Scan or API.
- Paid plan
- In USD: Pro $12.95/month billed yearly ($155.40/year) or $14.95/month billed monthly, 200K words/month. Enterprise $136.58/month billed yearly or $179/month billed monthly, 1.5M words/month. Extra team seats cost more.
- Signup
- Not stated clearly. The page offers a Continue for Free option and an FAQ says sign-up is needed for the full suite.
- Watermark
- Not stated.
- Where files go
- Privacy policy says submitted text is stored and processed on its servers and its providers' servers in Canada, the US and other places. Some features send text to OpenAI, which may keep logs up to 30 days. Scan history may be used to train models unless you opt out. Retention is as long as reasonably necessary.
From the tool's own pages, checked 2026-11-01. Sources: Pricing, Privacy policy. Prices and limits change; check the tool before you rely on them.
Details and sources
- Free tier
- Not stated. The pricing page lists only Starter and Premium plans. The home page says its live demos need no sign-up to try.
- Paid plan
- Starter and Premium, billed monthly or annually (annual marked Save 20%); currency selector shows USD. Exact prices were not readable on the page.
- Signup
- Not stated for the listed tasks. The home page says no sign-up is required to try the demos.
- Watermark
- Not stated.
- Where files go
- Privacy policy says it does not apply to text customers process with the services, so where that text goes and how long it is kept is not stated. Account data is kept while there is a business need.
From the tool's own pages, checked 2026-11-01. Sources: Pricing, Home page, Privacy policy. Prices and limits change; check the tool before you rely on them.
Details and sources
- Free tier
- The pricing page says there is no free trial. It labels some tools as Free (Paraphraser, Grammar Checker, Plagiarism API) but gives no limits.
- Paid plan
- In USD: All in One $9.99/month or $119.88/year; Plagiarism Checker $9.80/month or $94.08/year; Paraphraser $9.99/month or $76.70/year. Other tool-specific plans and Enterprise/LMS custom pricing are also listed. Billing country not stated.
- Signup
- Not stated.
- Watermark
- Not stated.
- Where files go
- Privacy policy says uploaded text is not saved and is removed right after the process runs, and images are deleted right after the request. Account and payment data of subscribers is kept. It does not say whether processing happens on the device.
From the tool's own pages, checked 2026-11-01. Sources: Pricing, Privacy policy. Prices and limits change; check the tool before you rely on them.
Details and sources
- Free tier
- Not stated.
- Paid plan
- Not stated.
- Signup
- An account is required for Copyscape Premium. The page says: “Sign up Copyscape Premium.”
- Watermark
- Not stated.
- Where files go
- Not stated.
From the tool's own pages, checked 2026-11-08. Sources: Home. Prices and limits change; check the tool before you rely on them.
Read automatically by a program, not by a person. Each fact quotes the sentence it came from, and a fact is shown only if that sentence is on the page. Where a page did not say, it reads “Not stated.”
Answers come from each tool's own pages (“Unclear” means they do not say). Tick “Compare” on two to four tools to read them side by side.
Also listed (3, not yet tested)
Each of these answered when we visited its site. We have not tested them or recorded facts, so they are in alphabetical order, not ranked.
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